Engine starter gearing



Dec. 9, 1952 A. R. 'roBlA's- 2,620,670

ENGINE STARTER `ummm:

med ocr. 17, 1951 IIIHII IN V EN TOR.

@uw 7e. 12M-6 WITNESS: BY Wal-2 M ATTORNEY Patented Dec. 9, 11952 ENGINE. STARTER GEARING YArthur R. Tobias, Elmira, N. Y., assignor to Bendix Aviation Corporation,

Delaware a corporation of Application October 17, 1951, Serial No. 251,679

The present invention relates to engine starter' gearing,l and more particularly to that type of automatically engaging drive which incorporates means for preventing premature cle-mesh of the drive pinion' responsive to a false start of the engine.

Drives of this general type which employ a centrifugal latch for holding the pinion in mesh until the starting motor has attain-ed 'a predetermined speed offer some'advantages over those controlled in -other ways, but as heretofore constructed have been somewhat subject to the disadvantage that if the operator open-s the starting switch too soon after the engine starts, the motor may knot reach the necessary speed to .release the latch, and the pini-on stay-s in mesh indefinitely while the engine is running.

VIt is an object of the present invention to provide a novel engine starter drive of the antik-ickout or follow through type in which the demesh of the starter pinion is controlled primarily by the speed of the starting motor` while the pinion is overrunning, whi-ch incorporates supplemental means responsive to engine speed for securing demesh of the pinion.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawing in which:

Fig. 1 is a side elevation partly broken away and in section of a preferred embodiment of the invention showing the parts in normal or idle position; and

Fig. 2 is a similar View showing the parts in the positions assumed when the starting pin-ion is overrunning the drive while held in mesh with the engine gear.

In Fig. 1 of the drawing there is illustrated a power shaft I on which a driving head 2 is fixedly mounted as by means of a cross pin 3. An anchor plate 4 is non-rotatably mounted on the drive head 2 against a shoulder 5 thereon, and is yieldably connected by a spring 6 with a similar anchor plate I non-rotatably mounted on the end of a screw shaft 8 against a shoulder 9. A control nut and driving overrunning clutch member I0 is threaded on the screw shaft 8, andis provided with clutch teeth I I normally engaging similar overrunning clutch teeth I 2 formed on a driven clutch member I3, which i-s splined on the extended hub I4 of a pinion I5, slidably journal-led on the power shaft I f0.1` engagement with an engine gear I6.

The driven overrunning clutch member I3 is retained on the pinion I5 by a lock ring Il, and

6 Claims. (Cl. 74-7) a mesh-enforcing spring I8 yieldably holds the pinion in extended relation to said clutch member.

A barrel member I9, non-rotatably mounted on the control nut I0, surrounds and encloses the clutch members, which are retained in the barrel by a lock ring 2|. A light clutch spring 22 is located between a shoulder 23 on the drivenv clutch member and a terminal flange 24 of the barrel so as to yieldingly hold the teeth II, I2 of the overrunning clutch members in engagement.

For ease in assembly, the screw shaft 8 is preferably formed in two interlocking parts as illustrated, held together by a sleeve 20 suitably anchored in the driving head 2.

A latch member 25 i-s slidably mounted for radial movement in the driving clutch member I0, and is yieldably pressed into engagement with the threads of the screw shaft 8 'by meansy of a spring 26. The screw shaft is provided with a should-er 2l so positioned as to be engaged by the latch 25 when the pinion I5 is meshed with the engine gear I6, and thereby prevent demeshing of the pinion until the rotational speed of the driving clutch mem-ber exceeds a pre.

determined minimum.

Means are provided for friction-ally transmitting sufficient torque from the pinion to the driving member, while the pinion is overrunning,y

to gradually accelerate the clutch member, screw shaft, and power shaft to a speed sufficient to release the latch, even though the starting motor (n-ot illustrated) which actuates the power shaft is deenergized. As here shown this is accomplished by means o-f a sleeve 28 journalled on the driving clutch member I0 and having a flange 29 provided with coupling lugs 3I adapted to engage similar lugs 32 on the driven coupling member I3 so as to cause the sleeve to rotate with thev driven coupling member while permitting sum# In operation, starting with the parts in thev positions illustrated in Fig. 1, rotation of thepower shaft in the direction of the arrow (a) isf transmitted through the spring 6 to the screw shaft 8, causing the driving clutch member and control nut IU to be traversed to the right. The' pinion I5 is thus moved through the driven clutch member I3 and spring I8 into mesh with the engine gear I6, the meshing movement being limited by engagement of the nut I with the ends 3T of the threads on the screw shaft. At this time, the latch 25 drops down behind the shoulder 21 on the screw shaft, thereby preventing demeshing Vmovement of the drive parts.

' When the engine res, the acceleration of the pinion I5 causes it to overrun the power shaft, while the clutch spring 22 yields to allow the teeth of the overrunning clutch members to ratchet over each other as shown in Fig. 2. If

it should be a false start, as soon as the powerV shaft attains corresponding speedwiththe enginev gear, cranking is resumed, the overrunning clutch members being reengaged by the spring 22.

When the engine becomes self-operative, torque is transmitted from the overrunning pinion and clutch member I3 through the sleeve 28, and frictionfspring :members 34, 35 to -.the libarrel I9 andtheclutch nut I. If the starting motor-.is maintained in operative condition by the operator, 4this torque lassists in accelerating the power shaft-I yto the speed'necessary -to retract the latch 25ffrom engagement with the shoulder 2 on thefscrew shaft, and thus permit lthe member I0 with-.itsassociated parts to be traversed backV to idle position..Y If the starting motor should be immediately deenergized when the engine becomes .self-operative, thel torque transmittedl through `the frictional drag `connection v311, .35 etc. will ,gradually accelerate the power shaft ,to the necessary speed to insure demesh vof 4the .pinion I 5 from the engine gear IB.

.Although but one .embodimentof Ythe invention has been shownand descri-bed in detail. it will be'understood that other embodiments are possible, .andi that various .changes may be made inl thedesign .and .arrangement ofthe parts with-v out departing from the spirit of the invention.

I claim: v

vl. In an engine starterv drive a power shaft, a

hollow screw shaft journalled thereon, yieldingl means for .connecting the screw shaft for rotation with the power shaft, a pinion slidably journalled on the-,power shaft, a control nut and driving overrunning lclutch member threaded on the lof torque from the sleeve to the control nut when the pinion overruns the control nut.

2. An engine starter drive as set forth in claim V`1 in which the drag means is in the form of coiled springs having frictional engagement with the sleeve and control nut, and with each other.

3. An engine starter drive as set forth in claim 2 in which the control nut and sleeve have anges between which the springs are located, and said Y springs are inter-threaded whereby; relative ro tation ybetween the-springs increases their -endwise pressure'against said flange.

4. 'An engine starter drive as setforthr in claim 1 includingfurther a barrel member enclosing the clutch, sleeve and spring members, and vmeans in the barrel yieldingly pressing the :clutch members into engagement. `5. In an engine starter drive a power shaft,V

a pinion slidably vjournalled on' the power "shaft for movement into and out of mesh `withia gear of an engineV to bestarted, means for traversing androtating the pinion including *an overrunning clutch, centrifugal meansV for yholding the'pinion in mesh "with the engine gear until the power shaft is rotating above-a predetermmedspeed; and frictional coupling means for transmitting 'a' controlled amount of torque from vthe pinion to the power shaft Awhen the pinion overruns.

6. An engine starter-drive as set forth in claim' 5 in which vthe frictional coupling meanscomprisesva pairof -interth-readedsprings and'v means cooperating therewith to rotate the power shaft from the Vpinion ata speed sufficient to :release the centrifugal holding means.

ARTHUR R. TOBIAS.

.No references cited. 

